A pressure sensor is utilized to sense the pressure difference between a detecting pressure and an atmospheric pressure or fluid pressure, and then convert the detected pressure difference into an electric signal. Pressure sensors can be utilized to measure pressures of gases or liquids and are employed in a wide range of industrial, commercial and consumer applications. Pressure measurements typically are taken in the context of absolute, gauge, or differential (or relative) measurements. An absolute pressure sensor represents a specific type of sensing device, which measures a pressure relative to a vacuum. A gauge sensor, on the other hand, measures a pressure relative to atmospheric pressure. A differential pressure sensor measures a pressure difference between two inputs.
A typical sensor package housing is configured from pre-molded plastic and includes a metal lead frame for providing interconnection to external circuitry. Such a package further includes a lid having an opening for directing external pressure to the sensor. Some prior art silicon pressure sensing die attach solutions attach a sensor die to the housing utilizing a soft adhesive (e.g., RTV, epoxy, etc.). In the case of an absolute pressure sensor, pressure is usually applied from the topside, whereas for gauge or differential pressure sensing, a pressure port is provided on the bottom side of the sensor device. Adhesives, soft or hard, however, are not considered hermetic and, over time, moisture and corrosive gases will penetrate the interface, causing the electronics of the pressure sensor to fail. Additionally, in certain applications the leakage of the media being sensed is undesirable. Also, the thermal coefficient of expansion of the adhesive is different than the thermal coefficient of expansion of silicon; hence, temperature changes can induce stresses in the structure.
Such pressure-sensing die attach solutions do not possess a wide range of media compatibility over the full desirable range of operational temperatures. Similarly, current material restrictions require engineers to specifically match media environment to the materials, thereby limiting the ability of one design to fit multiple environments. Typical solutions may provide media compatibility, but do not possess accuracy and stability over a wide temperature and pressure ranges. In such solutions, the electrical stability of the output signal also varies for a wide range of temperature and pressure due to a diverse coefficient of thermal expansion. Similarly, current post operational conditions require laser trimming to maintain the temperature compensation and linearization accuracy of the device, which can be very costly.
Based on the foregoing, it is believed that a need, therefore, exists for an improved pressure sensor system and method for attaching a sense die to a mounting surface via soldering and includes ASIC compensated output as described in greater detail herein.